Safely thaw frozen salmon filets. See blog post for safe thawing instructions.
Fill a large pot half way with water, and bring to a boil. Once boiling, pour in the lentils. Cover the pot, reduce the heat and simmer until the lentils are tender, but not mushy, about 20 minutes. When done, drain.
While the lentils are cooking: Make the lentil dressing - Take a handful of arugula (about 1.25 oz) and mince it. In a small bowl or ramekin, combine 1 tbsp of olive oil, 2 tbsp lemon juice, 1/4 tsp salt, and minced arugula. Mix well and set aside.
Chop up one onion and one yellow squash. Heat 1 tbsp of oil in a large skillet, and add the onion and squash. Push the vegetables to the sides of the skillet.
Sprinkle dried dill evenly over the flesh of the salmon.
Place the salmon filets skin side down in the middle of the pan. Cook until golden, about 4 minutes, then flip and cook an additional 4-5 minutes. Make sure you are stirring the vegetables on the outside of the pan while the salmon is cooking to prevent burning.
Place the drained lentils in a large mixing bowl, and mix in the lentil dressing, a handful of arugula and the cooked onion and squash. Spoon onto a plate, and top with a piece of salmon. Enjoy!